The present invention relates to apparatus for manipulating individual or stacked sheets of paper, foil, cardboard or the like. More particularly, the invention relates to improvements in apparatus for subdividing relatively large sheets of paper or the like into smaller sheets or leaves which can be used for the making of various types of stationery products, such as pads, books and the like. Still more particularly, the invention relates to improvements in apparatus of the type wherein sheets are severed by instrumentalities extending in the direction of transport of sheets toward and beyond the severing location or locations.
Presently known severing apparatus which are utilized to subdivide individual or stacked sheets into sets of two or more smaller sheets or leaves comprise a battery of severing or subdividing knives which are disposed at a severing station and are actuated at the same time to subdivide a sheet or a stack of sheets at such station into several (e.g., four) smaller sheets or leaves. The apparatus can further include trimming knives which are designed to remove the surplus from two lateral marginal portions of a sheet or stack of sheets at the severing station. Such apparatus operate quite satisfactorily as long as the sheets are relatively thin and/or as long as the height of stacks of superimposed sheets is rather low. However, once the height or thickness of a stack of sheets at the severing station exceeds a certain value, the apparatus of the above outlined character are incapable of doing an acceptable job, especially as concerns the quality of cuts and the accuracy of the trimming or surplus-removing operation. This is due to the fact that the leaves, which are obtained in response to simultaneous severing of a sheet or a stack of sheets at the single severing station, must yield sideways in order to account for the thicknesses of severing knives. However, there is no room to yield because each leaf is confined between two neighboring knives or between a severing knife and the adjacent trimming knife. Consequently, the leaves are compelled to bulge in the course of the severing operation which causes the formation of inferior cuts, namely, the planes of lateral edges of the freshly formed leaves are not normal to the planes of individual leaves. The quality of the cutting operation is also unsatisfactory in other respects, for example, because the lateral edges are not entirely straight due to progressive bulging of leaves in the course of simultaneous movement of two trimming knives and one or more severing or subdividing knives against and through the sheet or stack of sheets at the single severing station. Moreover, the removal of freshly formed leaves also presents problems, especially if the outline of the space which is available is such that there might be sufficient room, as considered in the direction of delivery of sheets to the single severing station, but not at right angles to such direction.